1. Field of the Invention
The present invention is directed to home phone line networks. More particularly, the present invention is directed to the delivery of power over home phone line networks.
2. Background
A. Home Phone Line Networks
Home networking is becoming increasingly popular. This increased popularity is due, in part, to an increase in the number of households with more than one personal computer (PC). According to the International Data Corporation (IDC), more than 20 million U.S. households have more than one computer. Additionally, market research indicates that consumers who currently own PCs are also the same consumers buying the majority of new computers. As a result, multi-computer households are becoming increasingly common. Home networks provide a variety of benefits to such multi-computer households. For example, home networks permit the users of multiple PCs to share a common printer, share files such as images, spreadsheets and documents, and access the Internet via a common network connection.
In addition to PCs, a wide variety of other devices may be attached to a home network including, but not limited to, PC peripheral devices, broadband media players, and telecommunication devices. For example, televisions and audio equipment can reside on a home network for receiving video and audio content over the Internet via a dial-up, cable, xDSL, or wireless connection. Additionally, VoIP (Voice over Internet Protocol) telephones can be connected to the home network for enabling Internet telephony via an external network connection.
Conventional home network types include home phone line, home power line, Ethernet, wireless connections, or some combination of the above. Home phone line networking is considered advantageous because it is relatively inexpensive and easy to install. Indeed, as the vast majority of U.S. homes include at least one phone line (and a majority of U.S. homes include two phone lines), home phone line networking typically does not require the installation of any additional wiring in the home.
Home phone line networking is often referred to as HomePNA or HPNA because it is based on specifications developed by the Home Phoneline Networking Alliance. The alliance is a consortium of networking technology companies that have created a phone line standard for the networking industry. HPNA uses a method known as Frequency Division Multiplexing (FDM) to permit voice and data to travel on the same phone line simultaneously without interfering with each other. HPNA 1.0, the original version of the standard, operates at 1 Mbps. The current specification, HPNA 2.0, operates at a faster 10 Mbps.
B. Internet Telephony Over Home Phone Line Networks
The use of a home phone line network for Internet telephony is particularly advantageous because it permits additional telephone numbers, and associated telephony devices, to be added to the customer premises without requiring the installation of additional telephone wire. This is in contrast to Plain Old Telephone Service (POTS), in which an additional wire pair must be installed in a home in order to support each additional phone number.
Where multiple telephony devices are connected to a home phone line network, multiple interfaces are required. The interface between a telephony device and a home phone line network may reside in an adapter or in the telephony device itself. In either case, it would be advantageous to provide power to the multiple interfaces from a single external power source. In this way, the circuitry for generating the power signal need not reside within the interface itself, thereby permitting the interface to be manufactured more cheaply. What is desired, then, is a system and method for providing power from a single power source to one or more devices, such as telephone adapters and/or telephones, over a home phone line network.
Additionally, it is anticipated that customers with Internet telephones residing on a home phone line network will expect lifeline service. Lifeline service entails the delivery of phone service even in the absence of power to the customer premises, as in the case of a power outage. POTS customers have become accustomed to lifeline service since POTS phones have traditionally been powered by a signal transmitted over the phone line from a telephone company's Central Office (CO). Accordingly, a system and method is desired for providing power to one or more telephony devices on a home phone line network from a source external to the customer premises. In light of the fact that many home phone line networks are interfaced via a residential gateway to data-over-cable systems, it would be beneficial to provide power from an external power source such as the HFC (hybrid fiber coaxial) network associated with a data-over-cable system.
Finally, home phone line networks by definition must be capable of supporting a variety of services for transporting both voice and data. Accordingly, the system and method for providing power over a home phone line network should be interoperable with other services that are delivered over the home phone line network, such as POTS and HPNA.